fix: Update the label name to use .strip to avoid unnecessary whitespace characters (#8541)

- The cache stores the labels as label1, label2. Without removing the whitespace, the output of cached_label_list_array would be [label1, [whitespace]label2], which doesn't match with the existing labels. This list is returned with proper label names.

app/models/conversation.rb

@@ -183,7 +183,7 @@ class Conversation < ApplicationRecord
   end
 
   def cached_label_list_array
-    (cached_label_list || '').split(',')
+    (cached_label_list || '').split(',').map(&:strip)
   end
 
   def notifiable_assignee_change?